Vertebral compression fractures involve the collapse of one or more vertebral bodies in the spine. Vertebral compression fractures or related spinal deformities may initiate, for instance, from metastatic diseases, injuries or osteoporosis.
Conventional surgery for treating vertebral compression, often referred to as vertebroplasty, includes a cannula or a needle inserted through the posterior of a targeted vertebral body, usually through the pedicles. Once positioned within the compressed vertebral body, bone cement is pushed through the needle into the vertebral body. Variations of vertebroplasty include the deployment of mechanical devices or expansion of a balloon to restore the height of the vertebral body and to create a void in a compressed vertebral body; bone cement is then inserted into the space to stabilize the devices and to strengthen the vertebral body.
In order to sufficiently access a vertebral body for complete infusion of cement it is known to use curved needle enabling interdigitation of the cement.
Such curved needles are often made of shape-memory alloys. For instance, WO 00/33909 discloses a needle assembly comprising a hollow, curved, superelastic infusion needle. The needle assembly comprises an infusion needle made of a superelastic material such as nitinol and an outer cannula for introduction into the body of a patient. The said rigid outer cannula is required as the initial access to the vertebral body must be made using a relatively straight approach. Upon deployment from the outer cannula, the needle cannula substantially returns to the preformed curved configuration for the introduction of materials at areas lateral to the entry path of the needle assembly. In order to avoid coring the bone tissue during introduction, a trocar is inserted inside the outer cannula during introduction; once the outer cannula has been directed to the target site, the trocar is removed and the infusion needle is inserted into the said outer cannula.
However, with such devices, the friction between the curved needle and the outer cannula prevents easy introduction of the curved needle. As a result, there is a need for device creating voids within tissue with reduced friction during insertion between the curved needle or rod and the outer cannula directed to the target site.
WO2014/093464 discloses a friction reduction covering sized to be received in a cannula and a cavity creation member, biased from a retracted to a deployed configuration, sized to be disposed in the friction reduction covering. With such devices, the curved needle is enclosed within a rigid covering. Consequently, there is reduced friction between the curved needle and the cannula during the surgical procedure. However, within WO2014/093464 the friction reduction covering is not secured to the handle and slides freely in at least one direction.
Therefore there is still of need for improved control of the deployment of the curved needle relative to the handle and/or the friction reduction covering.